The invention discloses a pressure-resistant housing of a deep-sea submersible, belonging to the field of deep-sea submersible. The pressure-resistant shell comprises an outer pressure-resistant spherical shell and an inner pressure-resistant spherical shell, and seawater is arranged in the cavity between the outer pressure-resistant spherical shell and the inner pressure-resistant spherical shell. A first relief valve is arranged on the outer side of the outer pressure-resistant spherical shell, a second relief valve is arranged on the outer side of the inner pressure-resistant spherical shell, and the second relief valve is arranged in a slow flow cavity on the inner pressure-resistant spherical shell; the outer side of the inner pressure-resistant spherical shell is also provided with ahigh-pressure gas cylinder which is connected with the cavity; an access hatch is arranged on the outer pressure spherical shell and the inner pressure spherical shell, an access hatch cover base isarranged on the outer pressure spherical shell and the inner pressure spherical shell at the access hatch, and an access hatch cover is arranged on the access hatch cover base; the invention solves the problem that the material requirement of the pressure-resistant shell is difficult to realize under the condition that the radius of the spherical shell with constant submergence is increased, and can ensure that the submergence is constant, and the external load of the structure is reduced while the radius of the spherical shell with constant submergence is increased, thereby ensuring the strength and stability of the structure.